'Up-scaling' potential for polyelectrolyte multilayer membranes

The layer-by-layer method is an attractive technique for preparing ultrathin nanostructured polyelectrolyte multilayer membranes (PEMMs) with tailored composition and tunable properties. This paper investigates the optimization of the membrane preparation to render it more feasible from a practical view point. PEMMs were prepared with minimal number of bilayers and rinsing steps for two polyion combinations: poly(diallyldimethylammonium chloride) with poly (vinylsulfonic acid sodium salt) and the same cation with poly(sodium 4-styrenesulfonate). Three bilayers proved optimal for SRNF applications. The commonly applied rinsing process turned out to be non-essential. In addition, two minutes dipping time per deposition step already proved sufficient for defect-free SRNF membrane preparation. Thus, the build-up protocol for PEMMs was overall reduced to a 6-step coating procedure taking 12 min without compromising the SRNF properties, in contrast to the previously reported 20-80 steps which required upto 7 h. Therefore, the 'up-scaling' potential of this type of membrane is significantly increased and potential production costs reduced.